Electro-chemical etching method for single crystal lanthanum hexaboride field emission arrays

The fabrication of LaB6 field emission arrays is the key technology for manufacturing LaB6 field emission cathodes. Silicon nitride film was deposited as mask layer on the (111) single crystal LaB6 substrate by plasma-enhanced chemical vapor deposition method, and then patterned to form an array of 4 μm diameter silicon nitride disks by reactive ion etching method. Using these Si3N4 disks as hard masks, the underlying LaB6 was etched to form tip field emission arrays by electro-chemical etching method. The etching mechanism was discussed, and the sample morphologies were investigated by SEM as the etching conditions changed. The experimental results indicated that H3PO4 could overcome the anisotropic phenomenon usually occurred in previous electro-chemical etching experiments. The emitter